Instrument transformers – Definition, types and connection

What is an instrument transformer? Instrument transformers are current and voltage transformation devices that are used to step down the transmission and distribution line voltages and currents to levels that can safely operate measuring instruments, protection devices and control relays by isolating it from the supply voltages. The above diagram shows the basic usage of … Read more

Difference between current transformers and Potential transformers

Current transformers (CT) and Potential Transformers (PT) are instrument transformer types used to step down transmission or distribution line voltages and current to the level that can be measured using measurement devices or controlled using control devices. The principle of operation of a certain type of CT and PT are similar to power transformers. Here … Read more

Potential transformers | Voltage transformers (PT)

Potential transformers (PT) or voltage transformers are instrument transformers used for voltage measurements. They are connected in parallel to the line and operates under the same principle of power transformers. They cannot be used used to supply raw power to the loads. They have an accurate voltage ratio and phase relationship between primary and secondary … Read more

Current transformers (CT)- working, types and connection

What is a current transformer? A current transformer is a type of instrument, used to measure or sense large alternating currents by scaling it to a smaller, safer and measurable value. It transforms the primary current to a proportional secondary value in terms of magnitude and phase. Current transformers are available in various sizes and … Read more

Transformer losses – Load losses and No-load losses

Some amount of power is lost during the voltage transformation process in a transformer. The current flows in a transformer winding and the alternating magnetic field in the core contributes to the majority of transformer losses.

Motor rated current v/s Full load current v/s Nominal current

The terms, motor rated current, full load current and nominal current, are very likely to confuse electrical engineers. Even though these terms are quite similar, there are slightly different from each other. Here is the clear definition of each one of them. Definitions Motor rated current The current drawn by a motor at its full … Read more

What is an Electric Motor?

An electric motor is an energy transformation machinery. It transforms electrical energy into mechanical energy. In other consumes electrical energy and delivers mechanical energy in the form of rotations. For example, an electric fan consists of a motor that draws electric energy from the mains and delivers kinetic energy (mechanical energy) in the form of … Read more

EMF equation of an alternator and solved problems

An alternator or a synchronous generator is a device used to convert mechanical energy to Alternating current electric current. The EMF equation of an alternator is a mathematical expression to calculate the effective value of EMF induced in each phase of an alternator or a synchronous generator. According to Faraday’s law of electromagnetic induction, the … Read more

EMF equation of DC machines

EMF equation of DC machines is a mathematical expression to calculate the EMF induced in a DC machine. As you know, the amount of EMF induced in a conductor depends on the number of turns of the coil and the rate of change of flux. Derivation of EMF equation of DC machines Consider a motor … Read more

EMF equation of transformers

EMF equation of transformers lets you calculate the RMS values of induced voltages in the primary and secondary windings of a transformer. An alternating voltage, when applied to the primary of a transformer, produces an alternating magnetic field which induces EMF in the secondary windings. The produced magnetic flux is alternating in nature and lags … Read more